Practice/deck editing mostly there

SVSim.EmulatedEntrypoint/Models/Dtos/Requests/ConfigUpdateFoilPreferredRequest.cs

@@ -0,0 +1,12 @@
+using MessagePack;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+[MessagePackObject]
+public class ConfigUpdateFoilPreferredRequest : BaseRequest
+{
+    [JsonPropertyName("is_foil_preferred")]
+    [Key("is_foil_preferred")]
+    public int IsFoilPreferred { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/Requests/ConfigUpdatePrizePreferredRequest.cs

@@ -0,0 +1,12 @@
+using MessagePack;
+using System.Text.Json.Serialization;
+
+namespace SVSim.EmulatedEntrypoint.Models.Dtos.Requests;
+
+[MessagePackObject]
+public class ConfigUpdatePrizePreferredRequest : BaseRequest
+{
+    [JsonPropertyName("is_prize_preferred")]
+    [Key("is_prize_preferred")]
+    public int IsPrizePreferred { get; set; }
+}

SVSim.EmulatedEntrypoint/Models/Dtos/UserDeck.cs

@@ -54,7 +54,32 @@ public class UserDeck
     public int Order { get; set; }
     [JsonPropertyName("create_deck_time")]
     [Key("create_deck_time")]
-    public DateTime DeckCreateTime { get; set; }
+    public DateTime? DeckCreateTime { get; set; }
+
+    /// <summary>
+    /// Empty placeholder matching the wire shape prod uses to pad deck-list responses up to the
+    /// per-format cap. The client's <c>DeckUI.DeckViewData.CreateDeckViewList</c> converts the
+    /// first entry whose <c>card_id_array</c> is empty into the "New Deck" tile, so at least one
+    /// of these must appear in any list the player can edit.
+    /// </summary>
+    public static UserDeck CreateEmptySlot(int deckNo) => new()
+    {
+        DeckNumber = deckNo,
+        ClassId = 1,
+        SleeveId = 3000011,
+        LeaderSkinId = 0,
+        Name = string.Empty,
+        Cards = new(),
+        IsCompleteDeck = 0,
+        RestrictedCardExists = false,
+        IsAvailable = 1,
+        MaintenanceCards = new(),
+        IncludesNonCollectibleCards = false,
+        IsRandomLeaderSkin = 0,
+        LeaderSkinIds = new() { 0 },
+        Order = 0,
+        DeckCreateTime = null,
+    };
 
     public UserDeck(ShadowverseDeckEntry deck)
     {